This invention relates to overhead conveyors where a hanger with an item of ware or work piece is suspended from one conveyor and transferred to another conveyor, and more specifically, to a linear transfer unit for moving a selected hanger and work piece from one conveyor to another.
Usually a conveyor moves a plurality of work pieces each suspended on a hanger, through and past one or more processing stations. Large work pieces may be suspended from two hangers. The work pieces so moved can be similar or dissimilar. In some situations it is desirable to transfer a hanger with a work piece from one conveyor to another. This has been done by a synchronous transfer unit, such as another conveyor or a transfer wheel, which operates synchronously with one conveyor to serially remove hangers and transfer the hangers to another conveyor, which operates synchronously with the transfer unit. The previously described system usually uses two (2) conveyors, one being a continuous conveyor and the other known as a power and free conveyor. The power and free conveyor provides the benefit that hangers can be linked in and out of the conveyor motion (i.e. they can be stopped for loading). Sometimes the transfer is between two continuous conveyors.
However, it is desirable in some situations to identify and selectively remove a hanger with a work piece from one conveyor for transfer to the other conveyor or vice versa. But the synchronous type of unit only transfers all hangers on a conveyor as they serially or sequentially approach the transfer unit rather than selected hangers.
Therefore it is an object of this invention to identify and select hangers associated with one conveyor and transfer the selected hanger to a second conveyor.
Usually the work pieces are on a hanger or hangers which include a hook. The hanger is suspended from the conveyor which also has hooks that couple with and engage the hanger hook. More specifically, the conveyor includes a plurality of outwardly opening hooks that are moved along the conveyor and the work piece hanger includes an inwardly open hook that engages and hangs from an outwardly open conveyor hook. In order to transfer a hanger from one conveyor to another, the orientation of the inwardly opening hanger hook must be such that it maintains its cooperative and coupling orientation relative to the outwardly open conveyor hooks. Usually this means that the hanger is retrieved from one conveyor, rotated 180.degree. about its vertical axis and then delivered to the other conveyor. Using a synchronous transfer wheel this hanger rotation occurs as the hanger is moved about the periphery or circumference of the transfer wheel.
It is another object of this invention to provide for identifying the hanger to be retrieved and retrieving the selected hanger from one conveyor, rotating the hanger 180.degree. about a vertical axis, and delivering the hanger and work piece to another conveyor or even to a specifically selected conveyor hook if need be.
The system of this invention can be used in the power and free/continuous or continuous/continuous situations.
These and other objects of this invention will become apparent from the following description and appended claims.